Place chicken in large soup pot that's not too wide. Cover with water. Add celery, onion and carrot. Bring to boiling. Reduce heat; add bay leaves and simmer, uncovered, for 1 hour 15 minutes, skimming scum as it rises to top.
Remove chicken from pot. Strain stock through colander lined with double-thickness dampened cheesecloth; reserve. Discard strained solids. Clean out pot. Return stock to pot. When cool enough to handle, skin and bone chicken. Cut in bite-size pieces.
Add celery, carrot and onion to stock. Simmer 20 minutes or until vegetables are tender. Add cabbage and bouillon; simmer 5 minutes. Add peas. Turn off heat. Let soup stand for 30 minutes. Add shredded chicken, pepper and butter. Gently reheat if necessary.